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bst_count_left_node.py
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66 lines (49 loc) · 1.43 KB
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"""
Write a function count_left_node returns the number of left children in the
tree. For example: the following tree has four left children (the nodes
storing the values 6, 3, 7, and 10):
9
/ \
6 12
/ \\ / \
3 8 10 15
/ \
7 18
count_left_node = 4
"""
import unittest
from bst import bst
def count_left_node(root):
if root is None:
return 0
elif root.left is None:
return count_left_node(root.right)
else:
return 1 + count_left_node(root.left) + count_left_node(root.right)
"""
The tree is created for testing:
9
/ \
6 12
/ \\ / \
3 8 10 15
/ \
7 18
count_left_node = 4
"""
class TestSuite(unittest.TestCase):
def setUp(self):
self.tree = bst()
self.tree.insert(9)
self.tree.insert(6)
self.tree.insert(12)
self.tree.insert(3)
self.tree.insert(8)
self.tree.insert(10)
self.tree.insert(15)
self.tree.insert(7)
self.tree.insert(18)
def test_count_left_node(self):
self.assertEqual(4, count_left_node(self.tree.root))
if __name__ == "__main__":
unittest.main()